This article explores liberal theology, one of the most important intellectual currents in Christian theology during the nineteenth and twentieth centuries. It explores its contribution to twentieth century Protestantism and its impact on the whole of Christian thought. Therefore, it first addresses the significance of this concept and the theological and philosophical elements of its emergence. Second, the paper investigates the most important stages of its development since the time of German theologian Friedrich Schleiermacher and explores the associated approaches, arguments, and problems. This makes it possible for us to discuss the value of this theological inclination as a reformist attempt equipped with methods of scientific and historical critique to study Christianity and the life of Christ, seeking to modernise the image of theology and expand its duties beyond its traditional identity as defined by Christian doctrine.